draft-ietf-appsawg-json-pointer-07.txt   draft-ietf-appsawg-json-pointer-08.txt 
Applications Area Working Group P. Bryan, Ed. Applications Area Working Group P. Bryan, Ed.
Internet-Draft Salesforce.com Internet-Draft Salesforce.com
Intended status: Informational K. Zyp Intended status: Standards Track K. Zyp
Expires: June 14, 2013 SitePen (USA) Expires: July 8, 2013 SitePen (USA)
M. Nottingham, Ed. M. Nottingham, Ed.
Akamai Akamai
December 11, 2012 January 4, 2013
JSON Pointer JavaScript Object Notation (JSON) Pointer
draft-ietf-appsawg-json-pointer-07 draft-ietf-appsawg-json-pointer-08
Abstract Abstract
JSON Pointer defines a string syntax for identifying a specific value JSON Pointer defines a string syntax for identifying a specific value
within a JSON document. within a JavaScript Object Notation (JSON) document.
Status of this Memo Status of this Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
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material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on June 14, 2013. This Internet-Draft will expire on July 8, 2013.
Copyright Notice Copyright Notice
Copyright (c) 2012 IETF Trust and the persons identified as the Copyright (c) 2013 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
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the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . 3 4. Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . 3
5. JSON String Representation . . . . . . . . . . . . . . . . . . 4 5. JSON String Representation . . . . . . . . . . . . . . . . . . 5
6. URI Fragment Identifier Representation . . . . . . . . . . . . 5 6. URI Fragment Identifier Representation . . . . . . . . . . . . 6
7. Error Handling . . . . . . . . . . . . . . . . . . . . . . . . 6 7. Error Handling . . . . . . . . . . . . . . . . . . . . . . . . 6
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7
9. Security Considerations . . . . . . . . . . . . . . . . . . . . 7 9. Security Considerations . . . . . . . . . . . . . . . . . . . . 7
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 7 10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 7
11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 7 11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 7
11.1. Normative References . . . . . . . . . . . . . . . . . . . 7 11.1. Normative References . . . . . . . . . . . . . . . . . . . 7
11.2. Informative References . . . . . . . . . . . . . . . . . . 7 11.2. Informative References . . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction 1. Introduction
This specification defines JSON Pointer, a string syntax for This specification defines JSON Pointer, a string syntax for
identifying a specific value within a JavaScript Object Notation identifying a specific value within a JavaScript Object Notation
(JSON) [RFC4627] document. It is intended to be easily expressed in (JSON) [RFC4627] document. It is intended to be easily expressed in
JSON string values as well as Uniform Resource Identifier (URI) JSON string values as well as Uniform Resource Identifier (URI)
[RFC3986] fragment identifiers. [RFC3986] fragment identifiers.
skipping to change at page 3, line 45 skipping to change at page 3, line 45
json-pointer = *( "/" reference-token ) json-pointer = *( "/" reference-token )
reference-token = *( unescaped / escaped ) reference-token = *( unescaped / escaped )
unescaped = %x00-2E / %x30-7D / %x7F-10FFFF unescaped = %x00-2E / %x30-7D / %x7F-10FFFF
; %x2F ('/') and %x7E ('~') are excluded from 'unescaped' ; %x2F ('/') and %x7E ('~') are excluded from 'unescaped'
escaped = "~" ( "0" / "1" ) escaped = "~" ( "0" / "1" )
; representing '~' and '/', respectively ; representing '~' and '/', respectively
It is an error condition if a JSON Pointer value does not conform to It is an error condition if a JSON Pointer value does not conform to
this syntax (see Section 7). this syntax (see Section 7).
Note that JSON Pointers are specified in characters, not as bytes.
4. Evaluation 4. Evaluation
Evaluation of a JSON Pointer begins with a reference to the root Evaluation of a JSON Pointer begins with a reference to the root
value of a JSON document and completes with a reference to some value value of a JSON document and completes with a reference to some value
within the document. Each reference token in the JSON Pointer is within the document. Each reference token in the JSON Pointer is
sequentially evaluated. By performing the substitutions in this sequentially evaluated.
order, an implementation avoids the error of turning '~01' first into
'~1' and then into '/', which would be incorrect (the string '~01'
correctly becomes '~1' after transformation).
Evaluation of each reference token begins by decoding any escaped Evaluation of each reference token begins by decoding any escaped
character sequence; this is performed by first transforming any character sequence; this is performed by first transforming any
occurrence of the sequence '~1' to '/', then transforming any occurrence of the sequence '~1' to '/', then transforming any
occurrence of the sequence '~0' to '~'. occurrence of the sequence '~0' to '~'. By performing the
substitutions in this order, an implementation avoids the error of
turning '~01' first into '~1' and then into '/', which would be
incorrect (the string '~01' correctly becomes '~1' after
transformation).
The reference token then modifies which value is referenced according The reference token then modifies which value is referenced according
to the following scheme: to the following scheme:
o If the currently referenced value is a JSON object, the new o If the currently referenced value is a JSON object, the new
referenced value is the object member with the name identified by referenced value is the object member with the name identified by
the reference token. The member name is equal to the token if it the reference token. The member name is equal to the token if it
has the same number of Unicode characters as token and their code has the same number of Unicode characters as token and their code
points are position-wise equal. No Unicode character points are position-wise equal. No Unicode character
normalization is performed. If a referenced member name is not normalization is performed. If a referenced member name is not
unique in an object, the member that is referenced is undefined, unique in an object, the member that is referenced is undefined,
and evaluation fails (see below). and evaluation fails (see below).
o If the currently referenced value is a JSON array, the reference o If the currently referenced value is a JSON array, the reference
token MUST contain either: token MUST contain either:
* characters that represent an unsigned base-10 integer value * characters comprised of digits (see ABNF below; note that
(possibly with leading zeros), making the new referenced value leading zeros are not allowed) that represent an unsigned
the array element with the zero-based index identified by the base-10 integer value, making the new referenced value the
array element with the zero-based index identified by the
token, or token, or
* exactly the single character "-", making the new referenced * exactly the single character "-", making the new referenced
value the (non-existant) member after the last array element. value the (non-existant) member after the last array element.
If a reference token is being evaluated against a JSON document, The ABNF syntax for array indices is:
implementations will evaluate each token against the document's
contents, and terminate evaluation with an error condition if it array-index = %x30 / ( %x31-39 *(%x30-39) )
fails to resolve a concrete value for any of the JSON pointer's ; "0", or digits without a leading "0"
reference tokens. See Section 7 for details.
Implementations will evaluate each reference token against the
document's contents, and terminate evaluation with an error condition
if it fails to resolve a concrete value for any of the JSON pointer's
reference tokens. For example, if an array is referenced with a non-
numeric token, it will fail. See Section 7 for details.
Note that the use of the "-" character to index an array will always Note that the use of the "-" character to index an array will always
result in such an error; applications of JSON Pointer thus need to result in such an error; applications of JSON Pointer thus need to
specify how it is to be handled, if it is to be useful. specify how it is to be handled, if it is to be useful.
5. JSON String Representation 5. JSON String Representation
A JSON Pointer can be represented in a JSON string value. Per A JSON Pointer can be represented in a JSON string value. Per
[RFC4627], Section 2.5, all instances of quotation mark '"' (%x22), [RFC4627], Section 2.5, all instances of quotation mark '"' (%x22),
reverse solidus '\' (%x5C) and control (%x00-1F) characters MUST be reverse solidus '\' (%x5C) and control (%x00-1F) characters MUST be
skipping to change at page 5, line 27 skipping to change at page 5, line 36
"e^f": 3, "e^f": 3,
"g|h": 4, "g|h": 4,
"i\\j": 5, "i\\j": 5,
"k\"l": 6, "k\"l": 6,
" ": 7, " ": 7,
"m~n": 8 "m~n": 8
} }
Then the following JSON strings evaluate to the accompanying values: Then the following JSON strings evaluate to the accompanying values:
"" // the whole document "" // the whole document
"/foo" ["bar", "baz"] "/foo" ["bar", "baz"]
"/foo/0" "bar" "/foo/0" "bar"
"/" 0 "/" 0
"/a~1b" 1 "/a~1b" 1
"/c%d" 2 "/c%d" 2
"/e^f" 3 "/e^f" 3
"/g|h" 4 "/g|h" 4
"/i\\j" 5 "/i\\j" 5
"/k\"l" 6 "/k\"l" 6
"/ " 7 "/ " 7
"/m~0n" 8 "/m~0n" 8
6. URI Fragment Identifier Representation 6. URI Fragment Identifier Representation
A JSON Pointer can be represented in a URI fragment identifier by A JSON Pointer can be represented in a URI fragment identifier by
encoding it into octets, using UTF-8 [RFC3629], percent-encoding encoding it into octets using UTF-8 [RFC3629], percent-encoding those
those characters not allowed by the fragment rule in [RFC3986]. characters not allowed by the fragment rule in [RFC3986].
Note that a given media type needs to nominate JSON Pointer as its Note that a given media type needs to specify JSON Pointer as its
fragment identifier syntax explicitly (usually, in its registration fragment identifier syntax explicitly (usually, in its registration
[RFC4288]); i.e., just because a document is JSON does not imply that [RFC4288]); i.e., just because a document is JSON does not imply that
JSON Pointer can be used as its fragment identifier syntax. In JSON Pointer can be used as its fragment identifier syntax. In
particular, the fragment identifier syntax for application/json is particular, the fragment identifier syntax for application/json is
not JSON Pointer. not JSON Pointer.
Given the same example document as above, the following URI fragment Given the same example document as above, the following URI fragment
identifiers evaluate to the accompanying values: identifiers evaluate to the accompanying values:
# // the whole document # // the whole document
#/foo ["bar", "baz"] #/foo ["bar", "baz"]
#/foo/0 "bar" #/foo/0 "bar"
#/ 0 #/ 0
#/a~1b 1 #/a~1b 1
#/c%25d 2 #/c%25d 2
#/e%5Ef 3 #/e%5Ef 3
#/g%7Ch 4 #/g%7Ch 4
#/i%5Cj 5 #/i%5Cj 5
#/k%22l 6 #/k%22l 6
#/%20 7 #/%20 7
#/m~0n 8 #/m~0n 8
7. Error Handling 7. Error Handling
In the event of an error condition, evaluation of the JSON Pointer In the event of an error condition, evaluation of the JSON Pointer
fails to complete. fails to complete.
This includes, but is not limited to: This includes, but is not limited to:
o Invalid pointer syntax o Invalid pointer syntax
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